Metal cleaning



Patented Feb. 9, 1937 UNITED STATES PATENT OFFICE 2,070,487 METAL CLEANING George Lutz, Rocky River, Ohio, assignor, by mesne assignments. to E. I. du Pont de Nemours & Company, W of Delaware 11, Del., a corporation 15 Claims.

This invention relates to the cleaning of metals, and is particularly directed to removing rust from, and rust-proofing, iron and steel articles by means of processes and compositions which employ phosphoric acid modified by the admixture of a sulfation product of an aliphatic compound which contains an alcoholic hydrocarbon radical of six or more carbon atoms.

Phosphoric acid is peculiarly adapted for use in the cleaning of iron and steel articles, and, de-

spit numerous disadvantageous characteristics, it

continues to be a favored material for this purpose. It is an excellent rust remover, and, by the formation of a phosphate film, it serves to protect the metal from .further rusting.

' Unfortunately there are numerous disadvantages inherent in the use of phosphoric acid solutions. Such solutions are difiicult to apply, especially to verticalsurfaces, because of their low viscosities and lack of adhesion. They also are diflicult to apply because the water in the solution quickly evaporates and then, of course, further spreading is impossible. These and numerous other diificulties have caused the use of phosphoric acid solutions to be a tedious and exacting task, and have caused the results obtained to-be none too satisfactory.

Realizing the deficiencies in the characteristics of phosphoric acid solutions, those working in :0 the art have attempted to enhance the value of such solutions by adding various modifying agents thereto. Glycerine, glucose, sulfonated aromatic compounds, alcohols, mono ethyl ether of ethylene glycol, and innumerable similar ma- !5 terials have been added to phosphoric acid solutions with indifferent success. The mixture is usually improved slightly in one respect, but other difliculties are aggravated until, in many instances, the mixture is of less utility than the original acid.

Such materials as glycerine and glucose increase the body of the acid and check the rapidity of its drying, but they interfere, to some extent, with the action of the acid on the metal.

:5 Alcohols and the like aid, to some extent, the action of the acid, but they{.decrease the viscosity and adhesiveness of the acid and, moreover, make it dry very quickly. Other additions tend to separate from the acid, while still others react after a time and render useless both acid and agent. p

I have found that the difiiculties and disadvantages which have heretofore harassed the 5 art can be overcome by modifying the characteristics of phosphoric acid solutions with sulfation products of certain aliphatic compounds. The acid and sulfation product exercise a mutually synergetic action which results in a modification of the clear mobile acid to form a viscous, or 5 in some. cases gelatinous, white, or opalescent, product. Despite the modification, the acid is still free to exercise its desirable qualities, and the sulfation product, likewise, contributes its desirable attributes. 10

My composition readily removes rust from iron and steel articles even tho they be greasy and dirty. The acid, aided by the sulfation product, forms an even and continuous phosphate film on the metal, thereby protecting it against fur- 15 ther rusting.

The composition exhibits a surprisingly great viscosity, and, consequently, it adheres tenaciously to articles upon which it is applied. The composition, moreover, remains moist and active on a metal surface for a considerable time, and, after its action is complete, it may readily be removed bywashing the metal with water.

The sulfation products with which I modify the characteristics of phosphoric acid may be designated: a sulfation product of an aliphatic compound which contains an alcoholic hydrocarbon radical of six or more carbon atoms.

The sulfation products referred to herein are obtained by reacting concentrated sulfuric acid, oleum, chlorosultcnic acid, or other sulfuric acid derivatives of strongly sulfonating properties, upon aliphatic compounds which'contain an alcoholic hydrocarbon radical of six or more carbon, atoms, or preferably, of eight or more carbon atoms. According to the best experimental evidence available, the sulfation products of. the alcohols are sulfuric acid esters of the probable formula ROSO3H with the possible inclusion of minor amounts of sulfonio acids. When esters of unsaturated alcohols are sulfated, the sulfuric acid adds itself to the double bond, but the evidence available is insuflicient to decide whether the products are sulfuric acid esters, sulfonic acids, or a mixture of such compounds.

As far as applicability to the purposes of my invention is concerned, the reaction products obtained by the action of sulfuric acid, etc. upon the alcohols or upon the unsaturated esters are entirely equivalent, and for the purposes of my invention I chose to call the products the sulfates of aliphatic compounds having an alcoholic radical of six or more carbon atoms. I believe that it is the presence of an aliphatic alcoholic hydrocarbon radical of six or more carbon atoms and a salt forming sulfur-oxygen group in the molecule that determines the applicability of compounds to my purposes.

As examples of aliphatic compounds from which the sulfates useful in my invention are derived, I may mention hexyl, octyl, decyl, oleyl, octadecyl, cetyl, dodecyl, carnaubyl, melissyl, tetradecyl, linoleyl, and ricinoleyl alcohols. As additional examples of aliphatic compounds the sulfation products of which are particularly adapted to the purposes of my invention, I may mention aliphatic esters and ethers which contain an alcoholic radical of at least six carbon atoms. I may use, for instance, acetyl-octyl-alcohol, stearo-glyceryl ether, oleo-glyceryl ether, and palmetto-glyceryl ether. As still further examples of starting materials, I may mention allphatic compounds which contain a chloro or other halogen group. In this connection it should be noted that when oleyl alcohol, for instance, is sulfated with chlorosulfonic acid, the treatment probably results in the introduction of a chlorogroup into some of the hydrocarbon radicals.

It is noted that ordinarily the starting material to be sulfated is a mixture of aliphatic compounds. This follows from the fact that the alcohols, esters, and ethers of the types mentioned are produced commercially as mixtures and not as pure compounds, and it would be a costly and useless procedure to separate a particular alcohol, for instance, from others equally suitable.

The sulfates obtained from primary alcohols, and their oxygen derivatives in which the alcoholic hydrocarbon radical contains eight to eighteen, inclusive, carbon atoms are peculiarly adapted to my purposes.

The sulfates of aliphatic compounds, such as those above mentioned, form soluble salts with such compounds as sodium carbonate, sodium hydroxide, potassium hydroxide, ammonium hydroxide, oxides and hydroxides of lithium, magnesium, etc., and with such amines as pyridine, piperidine, cyclohexylamine, monoand dialkyl cyclohexylamines, dicyclohexylamines, mono-, diand trialkylamines and mono-, diand trialkylolamines. I may use the sulfates in the form of such salts for the purposes of my invention. It is noted, tho obvious, that the expression sulfation product of an aliphatic compound which contains an alcoholic hydrocarbon radical of six or more carbon atoms is generic to salts of the type above discussed. The commercial salts frequently contain rather large amounts of impurities such as sodium sulfate, sodium chloride, etc., but these impurities do not interfere with the usefulness of the sulfates for the purposes of my invention.

Example 1.-My preferred composition was made by mixing three per cent of the sulfation product of a mixture of octadecyl and cetyl alcohols with a thirty-three per cent phosphoric acid solution. The mixture was then heated at about F. for about four hours. The product was an opalescent-white, semi-gelatinous material. Some of the material was applied to a rusty, vertical, steel panel. The product was still quite moist thirty minutes after its application. After about an hour, the material was washed off the panel with water. The rust was entirely removed and the clean metal was only slightly etched. It is noted that phosphoric acid alone etched a similar panel a great deal more.

The amount of sulfation product may be widely varied. I prefer to use from about two to seven per cent by weight of the sulfation prodnot of Example 1. The concentration of the phosphoric acid solution may alsobe rather widely varied, but I usually prefer to use a twentyfive to forty-five per cent solution.

The temperature of reaction is a very important factor in the production of a satisfactory composition. When the sulfation products and the phosphoric acid are allowed to react at room temperature, several days are required for the solution to reach a maximum thickness. The product, moreover, tends to separate into two layers, especially in warm weather. Such a product is fairly satisfactory, however, as it can be made homogeneous by shaking. If the reaction is conducted at boiling temperatures, the reaction is so rapid that the sulfation products entirely decompose and float to the top as a waxlike or oil-like layer. I usually prefer to conduct the reaction at about 100 F. to F. for about two to six hours. 7

I believe that my composition results from a partial decomposition of the sulfation products by phosphoric acid. This reaction probably leads to the formation of colloidal, or very finely divided, compounds which are highly hydrated. The amount of phosphoric acid used in the reaction is, no doubt, small, so that the greater part of the acid is still available for rust-removing and rust-proofing.

Example 2.The sulfates used were sodium salts of sulfation products of a mixture of primary, aliphatic alcohols the alcoholic radical of which contained an even number of carbon atoms from C12 to C18. The sulfates contained about thirty per cent sodium sulfate and a small amount of sodium chloride. Five per cent of the sulfates was added to a thirty-five per cent phosphoric acid solution, and the mixture allowed to stand for several days. The product had a pastelike consistency and a white color. The product tends to separate into two layers, but it can easily be remixed. The considerations as to acid concentration, temperature of reaction, etc. given in Example 1 are applicable here. It is noted, however, that I usually prefer to use the sulfates of this examplev in an amount between about five and ten per cent by weight.

Considered broadly, I may vary widely the amount used of any of the sulfates of aliphatic compounds which contain an alcoholic radical of no less than six carbon atoms. Generally I prefer to use between about two and'ten per cent by weight, but in every case the specific amount used depends upon the thickness of product desired and the amount of sulfate required to produce such thickness. If too small an amount of sulfate be used, some improvement will result, but the product will not be satisfactorily viscous. If too large an amount of sulfate be used, the product will be too thick, and, moreover, it will be unnecessarily expensive.

Considered broadly, the phosphoric acid concentration may be widely varied. I usually prefer to use a fifteen to forty-five per cent solution, while, more specifically, I prefer a thirty to thirty-five per cent solution.

Considered broadly, the time and temperature of reaction of the sulfates and phosphoric acid may be widely varied. Specifically, I prefer to react them about two to six hours at temperatures from 100 F. to 140 F. I may, however, conduct the reaction at other temperatures, such as room temperature, and for other lengths of time.

It will be readily apparent that my composition may contain other rust-proofing and rustremoving materials. I may, for instance, add smallamounts of suitable abrasive materials, solvents, and the like.

While I have shown certain specific compositions above, I do not intend to be limited thereto, the scope of my invention being apparent from the following claims:

I claim:

1. A composition for rust removing and rustproofing comprising phosphoric= acid modified with a sulfate of an aliphatic compound which contains an alcoholic radical of no less than six carbon atoms. 7

2. A composition for rust removing and rustproofing comprising phosphoric acid to which hasbeen added a minor amount of a sulfate of a.

primary alcohol of from eightto eighteen, inclusive, carbon atoms.

3. A composition for rust removing and rustproofing comprising phosphoric acidto which has been added a minor amount of a salt of a sulfate of an aliphatic compound which contains an alcoholic radical of no less than six carbon atoms.

4. A viscouscomposition for rust removing and rust-proofing comprising phosphoric acid to which has been added a minor amount of a salt of a sulfate of a primary alcohol of from eight to eighteen, inclusive, carbon atoms.

5. A viscous composition for rust removing and rust-proofing comprising a fifteen to fortyfive per' cent solution of phosphoric acid which has been modified by the addition of about two to ten per cent of a sulfate of an aliphatic compound which contains an alcoholic radical of no less than six carbon atoms.

6. A viscous composition for rust removing and rust-proofing comprising a fifteen to forty-five per cent solution of phosphoric acid which has been modified by the addition of about two to ten per cent of a salt of a sulfate of an aliphatic compound which contains an alcoholic radical of no less than six carbon atoms.

7. In a process for cleaning and rust-proofing iron or steel, the step comprising treating the article with a composition comprising phosphoric acid to which has been added a sulfate of an aliphatic compound which contains an alcoholic radical ofno less than six carbon atoms.

8. In a process for cleaning and rust-proofing iron or steel, the step comprising treating the article with a composition comprising phosphoric acid to which has been added a minor amount of a sulfate of a primary alcohol of from eight to eighteen, inclusive, carbon atoms.

9. In a process for cleaning and rust-proofing iron or steel, the step comprising treating the.

article with a composition comprising phosphoric acid to which has been added a minor amount of a salt of a sulfate of an aliphatic compound which contains an alcoholic radical of no less than six carbon atoms.

10. In a process for cleaning and rust-proofing iron or steel, the step comprising treating the article with a composition comprising phosphoric acid to which has been added a minor amount of a salt of a sulfate of a primary alcohol of from eight to eighteen, inclusive, carbon atoms.

11. In a process for cleaning and rust-proofing iron or steel, the step comprising treating the article with a composition comprising a fifteen to forty-five per cent solution of phosphoric acid which has been modified by the addition of about two to ten per cent of a sulfate of an aliphatic compound which contains an alcoholic radical of no less than six carbon atoms.

12. In a process for cleaning and rust-proofing iron or steel, the step comprising treating the article with a composition comprising a fifteen to forty-five per cent solution of phosphoric acid which has been modified by the addition of about two to tenper cent of a salt of a sulfate of an aliphatic compound which contains an alcoholic radical of no less than six carbon atoms.

13. In a process of preparing a rust removing and rust-proofing composition, the step comprising modifying a fifteen to forty-five per cent solution of phosphoric acid by adding thereto a minor amount of a sulfate of an aliphatic compound which contains an alcoholic radical of no less than six carbon atoms, and heating the mixture for about two to six hours at a temperature between about 100 F. and 140 F.

14. A composition for rust removing and rustproofing comprising phosphoric acid modified with a sulfation product of a mixture of octadecyl and cetyl alcohols.

15. A composition for rust removing and rustproofing comprising phosphoric acid modified with a sodium salt of a sulfation product of a commercial mixture of primary aliphatic alcohols the alcoholic radicals of which contain an even number of carbon atoms from Ci: to Cu.

GEORGE LU'IZ. 

